KR20130086462A - A method and a node for preventing a collision of networks communicating based on a csma/ca - Google Patents

Abstract

PURPOSE: A method capable of preventing a collision between networks which communicate based on a carrier sense multiple access/collision avoidance (CSMA/CA) mode and an object node thereof are provided to prevent a collision between neighboring networks by alternating a decreasing period of a back-off counter of nodes which are included in the same network of neighboring CSMA/CA base. CONSTITUTION: An allocating unit (620) allocates at least one neighboring node, a decreasing period of a back-off counter for an object node, a slot index for the object node, and a size of a contention window based on the number of at least one neighboring node. A setting unit (630) sets any one value which is selected based on the size of the contention window as a back-off counter value for the object node. A reducing unit (640) reduces the back-off counter value for the object node based on a channel state and the value of the allocated slot index. A transmitting unit (650) transmits data about the at least one neighboring node according to the value of the back-off counter. [Reference numerals] (610) Synchronizing unit; (620) Allocating unit; (630) Setting unit; (640) Reducing unit; (650) Transmitting unit

Description

A method and a node for preventing collision between networks communicating based on the CSM / CA method {A METHOD AND A NODE FOR PREVENTING A COLLISION OF NETWORKS COMMUNICATING BASED ON A CSMA / CA}

The following embodiments relate to a method and a target node for preventing collision between networks communicating based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme.

The general CSMA / CA approach does not consider the situation where multiple homogeneous networks coexist. Collisions caused by signals from neighboring networks (networks), which occur frequently in a coexistence situation, may result in a contention window (CW) size selection range of the back-off counter of nodes included in the network. Increase to the maximum value of. As a result, as the number of nodes participating in the contention increases, the probability of collision increases, and accordingly, the value of the backoff counter taken by each node increases, thereby reducing the efficiency of resource utilization.

In particular, when homogeneous networks are in close proximity in a narrow area, the possibility of collision and deterioration of efficiency is also increased.

According to an embodiment, a method of preventing collision between networks communicating based on a CSMA / CA scheme may include at least one neighboring network and a target network communicating based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme. Synchronizing; A reduction period of a backoff counter for the at least one neighboring network and the target network, a slot index for the target network and a contention window, based on the number of the at least one neighboring network Allocating the size of the; Setting a value selected based on the size of the contention window as a back-off counter value for the target network; Decrementing a value of a backoff counter for the target network based on a state of a channel and a value of the assigned slot index; And transmitting data for the at least one neighbor network according to the value of the backoff counter.

The synchronizing may include synchronizing a time period between the at least one neighboring network and the target network by a first time period based on the number of the at least one neighboring network, and synchronizing a time period within the target network with the first time. Synchronization may be by a second time period that is distinct from the period.

The step of assigning a slot index for the target network comprises: a slot index for the target network using a system parameter including at least one of a beacon shifting sequence index and a network ID. ) Can be assigned.

Decreasing the value of a backoff counter for the target network includes determining whether the channel state is idle and the assigned slot index matches the index of the time slots for the at least one neighboring network and the target network. Based on the value of the backoff counter for the target network.

The method may further include resuming the contention for the data transmission based on whether the response to the data transmission is received.

Determining whether the size of the contention window for the target network is smaller than the size of the maximum contention window for the at least one neighboring network and the target network; And increasing the contention window size for the target network based on the determination result, and resuming contention for the data transmission comprises: increasing the contention window size for the increased target network. And may resume the competition for the data transmission on the basis.

According to an embodiment, a method of preventing collision between networks communicating based on a CSMA / CA scheme may include at least one neighboring network and a target network communicating based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme. Synchronizing; Based on the number of the at least one neighboring network, allocating a reduction period of a backoff count for the at least one neighboring network and the target network, a slot index for the target network, and a size of a contention window Making; Setting a value selected based on the size of the contention window as a back-off counter value for the target network; Decrementing a value of a backoff counter for the target network based on a state of a channel; And based on whether a value of the backoff counter matches a first value and whether a value of a slot index for the target network matches a time slot for the at least one neighboring network and the target network. Transmitting data for a neighbor network of the network.

The synchronizing may include synchronizing a time period between the at least one neighboring network and the target network by a first time period based on the number of the at least one neighboring network, and synchronizing a time period within the target network with the first time. Synchronization may be by a second time period that is distinct from the period.

The step of assigning a slot index for the target network comprises: a slot index for the target network using a system parameter including at least one of a beacon shifting sequence index and a network ID. ) Can be assigned.

Decreasing the value of the backoff counter for the target network may be reducing the value of the backoff counter for the target network based on whether the state of the channel is idle.

The method may further include resuming the contention for the data transmission based on whether the response to the data transmission is received.

Determining whether the size of the contention window for the target network is smaller than the size of the maximum contention window for the at least one neighboring network and the target network; And increasing the contention window size for the target network based on the determination result, and resuming contention for the data transmission comprises: increasing the contention window size for the increased target network. And may resume the competition for the data transmission on the basis.

The target node preventing collision between networks communicating based on the CSMA / CA scheme according to an embodiment includes at least one neighboring node and the target node communicating based on the CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) scheme. A synchronization unit for synchronizing; A reduction period of a backoff counter for the at least one neighbor node and the target node, a slot index for the target node, and a content window based on the number of the at least one neighbor node; An allocating unit for allocating a size of the; A setting unit configured to set a value selected based on the contention window size as a back-off counter value for the target node; A reduction unit for decreasing a value of a backoff counter for the target node based on a state of a channel and a value of the assigned slot index; And a transmitter configured to transmit data for the at least one neighboring node according to the value of the backoff counter.

The synchronization unit synchronizes a time period between the at least one neighboring node and the target node by a first time period based on the number of the at least one neighboring node, and synchronizes a time period in the target node with the first time period. Synchronization may be by distinct second time periods.

The allocator may allocate a slot index for the target node using a system parameter including at least one of a beacon shifting sequence index and a network ID.

The decrement unit may determine whether the channel state is in an idle state and the assigned slot index matches an index of a time slot for the at least one neighboring node and the target node. You can decrease the value.

The target node preventing collision between networks communicating based on the CSMA / CA scheme according to an embodiment includes at least one neighboring node and the target node communicating based on the CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) scheme. A synchronization unit for synchronizing; Based on the number of the at least one neighbor node, allocating a reduction period of a backoff count for the at least one neighbor node and the target node, a slot index for the target node, and a size of a content window. Allocating unit; A setting unit configured to set a value selected based on the contention window size as a back-off counter value for the target node; A reduction unit for reducing a value of a backoff counter for the target node based on a state of a channel; And based on whether a value of the backoff counter matches a first value and whether a value of a slot index for the target node matches a time slot for the at least one neighbor node and a target node. It includes a transmitter for transmitting data for the neighboring node of.

The synchronization unit synchronizes a time period between the at least one neighboring node and the target node by a first time period based on the number of the at least one neighboring node, and synchronizes a time period in the target node with the first time period. Synchronization may be by distinct second time periods.

The reducer may decrease a value of a backoff counter for the target node based on whether the state of the channel is idle.

According to an embodiment, the reduction periods of the backoff counters of the nodes included in the neighboring CSMA / CA-based homogeneous networks are staggered to prevent collisions between neighboring networks (networks), thereby increasing resource efficiency. Can be.

FIG. 1 is a diagram illustrating a case where a signal collision occurs between communicating networks based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme.
FIG. 2 is a diagram illustrating a method of adjusting a reduction period of a backoff counter used in a method for preventing collision between networks communicating based on a CSMA / CA scheme according to an embodiment.
FIG. 3 is a diagram for describing a method of controlling a reduction period of a backoff counter used in a method of preventing collision between networks communicating based on a CSMA / CA scheme according to another embodiment.
4 is a flowchart illustrating a method of preventing a collision between networks communicating based on a CSMA / CA scheme according to an embodiment.
5 is a flowchart illustrating a method of preventing a collision between networks communicating based on a CSMA / CA scheme according to another embodiment.
6 is a block diagram of a target node preventing collision between networks communicating based on a CSMA / CA scheme according to an embodiment.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. Also, like reference numerals in the drawings denote like elements.

FIG. 1 is a diagram illustrating a case where a signal collision occurs between communicating networks based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme.

Referring to FIG. 1, in an environment where homogeneous networks exist in close proximity to each other, collisions with signals transmitted from neighboring networks may occur even without collision between signals transmitted in the corresponding networks, thereby increasing the probability of collision. Here, the homogeneous network may include networks (here, Network 0 110 and Network 1 130) communicating based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme.

In particular, when each of the nodes included in each network operates according to the same time period, and the decrement period of the back-off counter of each of the nodes is the same as shown in Figure 1, collision is inevitable.

This collision probability increases rapidly as the number of neighboring networks increases. As the number of collisions increases, the amount of data lost is increased, and the size of the contention window (CW size) set by the nodes is closer to the size of the maximum contention window (CW _max ) that the nodes can select. .

In FIG. 1, both Node A 115 belonging to Network 0 110 and Node B 135 belonging to Network 1 130 determine the size of the contention window as the size of the maximum contention window CW _max . , '5'), the length of the contention period becomes longer and resource efficiency is lowered.

FIG. 2 is a diagram illustrating a method of adjusting a reduction period of a backoff counter used in a method for preventing collision between networks communicating based on a CSMA / CA scheme according to an embodiment. Referring to FIG. 2, it can be seen that two networks communicating based on the CSMA / CA scheme coexist.

At this time, the node A 215 included in Network 0 210 among the networks communicating based on the CSMA / CA scheme has a backoff counter only when slot index = 2k (where k is a natural number). The node B 235 included in the network 1 230 may decrease the back-off counter only when the slot index = 2k + 1 staggered with the node A 215. In this way, neighboring Network 0 210 and Network 1 230 do not overlap the transmission time point, thereby preventing collision.

If N networks coexist, each network has a slot index = Nk + n (n = 0, 1, ..., N-1), where N is the number of networks and k is any It is possible to decrement the backoff counter only in that slot by selecting n of any one of Here, a time slot (interval) in which the backoff counter is decreased may be referred to as a 'decrement period of the backoff counter'.

The decrement period of the backoff counter may be determined based on the number of co-existing networks. For example, as shown in FIG. 2, the target network (here, Network 0 210) and one neighboring network (here, Network 1 (230)) may be determined. In case of coexistence, it may be a decrement period of the bivalent backoff counter, which is the total number of networks. Therefore, in FIG. 2, the backoff counter of the target node (here, Node A 210) may be decreased by one for every two Contention slot indexes. Here, the contention slot index means an index of a time slot for at least one neighboring network and a target network.

If the number of neighboring networks is large, the efficiency of time resources is drastically reduced. Accordingly, when the number of neighboring networks is too large, one slot index may be allocated to several networks to be used jointly. If one slot index is used jointly, the efficiency of resource utilization can be improved.

FIG. 3 is a diagram for describing a method of controlling a reduction period of a backoff counter used in a method for preventing collision between networks communicating based on a CSMA / CA scheme according to another embodiment.

Unlike the method shown in FIG. 2, in FIG. 3, the backoff counter does not always decrease only in a given slot index. Instead, the data is not transmitted immediately when the value of the backoff counter reaches '0', and an index of a time slot for at least one neighboring network and a target network, that is, a contention slot index corresponds to a slot index assigned to the network. After confirming whether or not, data can be transmitted.

That is, in FIG. 3, Node A 315 included in Network 0 310 transmits only in a slot having a Contention slot index of 2k, and Node B 335 included in Network 1 330 has a Contention slot index of 2k +. It only transmits in slot 1, which prevents collisions between networks.

If N networks coexist, each network may select one n of slot index = Nk + n (n = 0, 1, ..., N-1) and transmit data only in the corresponding slot.

Here, the allocation of transmission slots by the number of neighboring at least one network reduces the efficiency of time resources and increases the possibility of collision in the network.

In this case, several networks can use one slot index jointly, resulting in an increase in the efficiency of resource utilization.

As described above with reference to FIGS. 2 and 3, in order to prevent a collision between networks by a method of adjusting a reduction period of a backoff counter, a process of synchronizing time, that is, synchronization between neighboring networks, is required. This ensures that the index of the current time slot recognized by each network (i.e., the Contention slot index, which is the index of the time slot for at least one neighboring network and the destination network) matches, preventing each network from transmitting in the same slot. have.

At this time, the unit of time synchronization between networks to be matched by synchronization is not necessarily one slot. This is because the values that each network references to avoid collisions are relative indexes, not exact indexes of slots.

For example, in a situation where N networks coexist, the time synchronization unit between the networks becomes N slots instead of 1 slots, and a value referred to by each network for adjusting the reduction period is a slot index mod N. Can be.

Accordingly, each network may use a two-step synchronization control method in which time synchronization between networks is set by N slot periods, and time synchronization in the network is set by one slot.

In addition, in order to prevent the collision of the network by adjusting the decrement period of the backoff counter, a negotiation process between networks may be required to set the slot index of the backoff counter allocated to each network.

However, such negotiations between networks can lead to increased system complexity and reduced efficiency of resource usage. Therefore, in one embodiment, the above damages can be prevented by utilizing system parameters instead of negotiation between networks.

One embodiment utilizes system parameters with reference to 802.15.6 BAN, which is a representative CSMA / CA-enabled system, but is not necessarily limited thereto.

The first example of using system parameters is to use a beacon shifting sequence index.

Here, beacon shifting is one of the 802.15.6 coexistence strategies, in which the beacon positions are randomly generated in order to prevent the beacons of neighboring networks from constantly colliding. This is how you change it every super frame. In this case, each network uses a different sequence to prevent collision, and for this purpose, different beacon shifting sequence indexes may be set (see Table 1 below). In one embodiment, the beacon movement order index may be used as a decreasing slot index of the backoff counter to omit additional inter-network negotiation.

A second example of using system parameters is to compare network IDs of each network and set slot indexes.

Recognition of the coexistence situation is possible through the continuous detection of a signal with a certain network ID as the destination. Therefore, in an embodiment, the obtained network IDs may be compared with each other, and set to a decreasing slot index of the backoff counter in order of magnitude.

For example, if the network IDs of coexisting networks are 100, 101, .., 100 + N-1, Nk + 0, Nk + 1, .., Nk + N-1 are respectively decremented by the backoff counter. Can be set to the slot index. In this way, additional network negotiation can be omitted by setting the slot index of the backoff counter by comparing the network IDs.

4 is a flowchart illustrating a method of preventing a collision between networks communicating based on a CSMA / CA scheme according to an embodiment.

In order to prevent collisions between networks communicating based on the CSMA / CA scheme as in an embodiment, first, after recognizing the existence of a neighboring network, that is, at least one neighboring network, at least one neighboring network and a target network Time synchronization can be achieved. The reason for this time synchronization is to match the indexes of the current time slots recognized by each network (that is, the contention slot index, which is an index of time slots for at least one neighboring network and the target network), so that each network has the same time slot. This is to prevent data transmission from

That is, in one embodiment, the at least one neighboring network and the target network communicating based on the CSMA / CA scheme operate according to the same time period by adjusting time synchronization, but each backoff counter of the nodes included in each network is operated. Stagger the decrement periods of the back-off counters. In this case, the target network may include a target node and at least one neighbor network may include at least one neighbor node.

Referring to FIG. 4, the target node included in the target network performs synchronization with at least one neighboring network that communicates based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme (401). In this case, the target node may synchronize a time period between at least one neighboring network and the target network by a first time period (eg, N slot period) based on the number of at least one neighboring network. The target node may synchronize the time period in the target network by a second time period (eg, one slot period) that is distinguished from the first time period. The target node according to an embodiment may synchronize the target network with at least one neighboring network by the above-described two-step synchronization control method.

The target node may determine the number of at least one neighboring network (or at least one neighboring node).

The target node allocates a reduction period of the backoff counter for the at least one neighboring network and the target network and a slot index for the target network based on the number of the at least one neighboring network (403). In addition, the target node may allocate (or set) a contention window value (CW) smaller than the value of the maximum contention window, that is, CW _max , which is used in a non-coexistence situation to prevent deterioration of resource utilization efficiency.

In operation 403, the target node may allocate a slot index for the target network using a system parameter including at least one of a beacon shifting sequence index and a network ID.

The target node sets a value of any one selected based on the size of the contention window as a back-off counter value for the target network (405). For example, the target node may randomly select one of the numbers from '1' to the size value CW of the contention window, that is, between [1, CW], and set the backoff counter value.

The target node then decrements the value of the backoff counter for the target network based on the state of the channel and the value of the assigned slot index.

More specifically, the target node determines whether the channel state is in an idle state (407). If the state of the channel is idle at 407, the target node determines whether the slot index assigned to the target network matches the index of the time slot for the at least one neighboring network and the target network (e.g., contention slot index). It may be (409). That is, the target node may determine whether the index of the synchronized time slot corresponds to the slot allocated to the network to which it belongs (here, the target network). If at 407 the state of the channel is not idle, or at 409 the slot index assigned to the target network does not match the index of the time slot for at least one neighboring network and the target network, the target node goes to 407 and the channel Can wait until the state of is idle.

If the channel state is idle and the slot index assigned to the target network matches the index of the time slot, the target node decrements the value of the backoff counter for the target network by one (411).

After repeating this process, when the value of the backoff counter becomes '0', the target node may transmit data.

The target node may check whether the value of the backoff counter is equal to '0' (413). If the value of the backoff counter matches '0' at 413, the target network transmits data for at least one neighboring network (415). On the other hand, if the value of the backoff counter is not '0', the target node may perform operation 407.

The target node may resume the competition for data transmission based on a response to the data transmission, that is, whether an ACK indicating successful transmission from the receiving end after transmission is received. That is, the target network may check whether an ACK for the data transmitted in 415 is received (417). If the acknowledgment is received at 417, the target network may end the operation. On the other hand, if the acknowledgment is not received at 417, the target node may determine whether the contention window size for the target network is smaller than the maximum contention window size for the at least one neighboring network and the target network. (419).

If the size of the contention window for the target network at 419 is smaller than the size of the maximum contention window (CW _max ), then the target node doubles the size of the contention window for the target network, and then goes back to 405 to match the contention ( contention).

If the contention window size for the target network has already reached the maximum contention window size at 419, the target node no longer increases the contention window size for the target network, and re-enters the contention. .

5 is a flowchart illustrating a method of preventing a collision between networks communicating based on a CSMA / CA scheme according to another embodiment.

As described above with reference to FIG. 4, in order to prevent collisions between networks communicating based on the CSMA / CA scheme, first recognize the existence of at least one neighboring network, that is, at least one neighboring network. A time synchronization between the network and the target network can be achieved.

The target node included in the target network performs synchronization with at least one neighboring network that communicates based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme (501). In this case, the target node may synchronize a time period between at least one neighboring network and the target network by a first time period (eg, N slot period) based on the number of at least one neighboring network. The target node may synchronize the time period in the target network by a second time period (eg, one slot period) that is distinguished from the first time period. The target node according to an embodiment may synchronize the target network with at least one neighboring network by the above-described two-step synchronization control method.

The target node may determine the number of at least one neighboring network (or at least one neighboring node).

The target node allocates a reduction period of the backoff counter for the at least one neighboring network and the target network and a slot index for the target network based on the number of the at least one neighboring network (503). In addition, the target node allocates (or sets) a new contention window size (CW) that is smaller than the maximum contention window size (CW _max ) used in the non-coexistence situation to prevent resource utilization efficiency degradation at 503. )can do.

In operation 503, the target node may allocate a slot index for the target network using a system parameter including at least one of a beacon shifting sequence index and a network ID.

The target node sets a value of any one selected based on the size of the contention window as a back-off counter value for the target network (505). For example, the target node may randomly select one of the numbers from '1' to the size value CW of the contention window, that is, between [1, CW], and set the backoff counter value.

The target node then decrements the value of the backoff counter for the target network based on the state of the channel.

More specifically, the target node determines whether the channel state is idle (507). If the state of the channel is idle at 507, the target node decrements the value of the backoff counter by 1 for the target network (509). On the other hand, if the state of the channel is not idle at 507, the target node may wait until the state of the channel is idle.

Thereafter, the target node determines whether the value of the backoff counter matches the first value (eg, '0'), and the value of the slot index for the target network is at least one neighboring network and a time slot for the target network. Based on whether or not, and may transmit data for at least one neighboring network.

More specifically, the target node may check whether the value of the backoff counter matches '0' (511). If the value of the backoff counter matches '0' at 511, the target node may determine whether the slot index allocated to the target network matches the index of the time slot for at least one neighboring network and the target network ( 513). That is, the target node may determine whether the index of the synchronized time slot corresponds to the slot allocated to the network to which it belongs (here, the target network). In this case, the target node may also determine whether the channel state is idle.

On the other hand, if the value of the backoff counter does not match '0' at 511, the target node may go to 507 and perform a corresponding operation.

If it is determined at 513 that the slot index assigned to the target network matches the index of the time slots for the at least one neighboring network and the target network, and the state of the channel is in the idle state, then the target node determines data for the at least one neighboring network. Transmit (515). If the slot index allocated to the target network at 513 does not match the index of the time slot for at least one neighboring network and the target network, or if it is determined that the channel state is not idle, the target node corresponding condition is satisfied. You can wait until

Thereafter, the target node may resume contention for data transmission based on a response to the data transmission, that is, whether an ACK indicating successful transmission from the receiving end after transmission is received.

The target node may determine whether an ACK for the data transmitted in 515 is received (517). If the acknowledgment was received at 517, the target network may end the operation. On the other hand, if the acknowledgment is not received at 517, the target node may determine whether the contention window size for the target network is smaller than the size of the maximum contention window for the at least one neighboring network and the target network. (519).

If the size of the contention window for the target network is less than the maximum contention window (CW _max ) at 519, then the target node doubles the size of the contention window for the target network, and goes back to 505 to match the contention ( contention).

If the contention window size for the target network has already reached the maximum contention window size at 519, the target node no longer increases the contention window size for the target network, and participates in contention again. .

6 is a block diagram of a target node preventing collision between networks communicating based on a CSMA / CA scheme according to an embodiment.

Referring to FIG. 6, the target node 600 according to an embodiment may include a synchronizer 610, an allocator 620, a setter 630, a reducer 640, and a transmitter 650. have.

The synchronization unit 610 synchronizes at least one neighboring node and a target node to communicate with each other based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme. The synchronization unit 610 synchronizes a time period between at least one neighboring node and the target node by a first time period based on the number of at least one neighboring node, and distinguishes a time period in the target node from the first time period. Synchronization may be by a second time period.

The allocator 620 may reduce the period of the backoff counter for the at least one neighboring node and the target node, a slot index for the target node, and a contention window based on the number of the at least one neighboring node. Window) size. The allocator 620 may allocate a slot index for the target network using a system parameter including at least one of a beacon shifting sequence index and a network ID.

The setting unit 630 sets any one value selected based on the size of the contention window as a back-off counter value for the target node.

The reducer 640 decreases the value of the backoff counter for the target node based on the state of the channel and the value of the assigned slot index. The reduction unit 640 may determine whether the channel state is idle and whether the slot index assigned to the target node matches the index of the time slot for at least one neighboring node and the target node. Can be reduced.

The transmitter 650 transmits data for at least one neighbor network according to the value of the backoff counter.

Also, the reducer 640 may decrease the value of the backoff counter for the target node based on the state of the channel, more specifically, based on whether the state of the channel is idle.

In this case, the transmitter 650 may determine whether the value of the backoff counter matches the first value and whether the value of the slot index for the target node matches the time slot for the at least one neighbor node and the target node. In addition, data for at least one neighboring node may be transmitted.

The method according to an embodiment of the present invention can be implemented in the form of a program command which can be executed through various computer means and recorded in a computer-readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be construed as being limited to the embodiments described, but should be determined by equivalents to the appended claims, as well as the appended claims.

610: synchronization unit
620: allocation unit
630: setting unit
640: reduction part
650: transmission unit

Claims (20)

Synchronizing at least one neighboring network and a target network in communication based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme;
A reduction period of a backoff counter for the at least one neighboring network and the target network, a slot index for the target network and a contention window, based on the number of the at least one neighboring network Allocating the size of the;
Setting a value selected based on the size of the contention window as a back-off counter value for the target network;
Decrementing a value of a backoff counter for the target network based on a state of a channel and a value of the assigned slot index; And
Transmitting data for the at least one neighbor network according to the value of the backoff counter.
Method for preventing a collision between networks communicating based on the CSMA / CA scheme comprising. The method of claim 1,
The synchronizing step
Synchronize a time period between the at least one neighboring network and the target network by a first time period based on the number of the at least one neighboring network,
A method for preventing collisions between networks communicating based on a CSMA / CA scheme that synchronizes a time period within the target network by a second time period distinct from the first time period. The method of claim 1,
Allocating a slot index for the target network
Between networks communicating based on the CSMA / CA scheme of allocating a slot index for the target network using a system parameter including at least one of a beacon shifting sequence index and a network ID. How to avoid the crash. The method of claim 1,
Decreasing the value of the backoff counter for the target network
Decrease the value of the backoff counter for the target network based on whether the channel state is idle and the assigned slot index matches the index of the time slots for the at least one neighboring network and the target network. A method for preventing collision between networks communicating based on CSMA / CA scheme. The method of claim 1,
Resuming contention for the data transmission based on whether a response to the data transmission has been received.
How to prevent the collision between the networks communicating based on the CSMA / CA method further comprising. The method of claim 5,
Determining whether the size of the contention window for the target network is smaller than the size of the maximum contention window for the at least one neighboring network and the target network; And
Increasing the contention window size for the target network based on the determination result;
Further comprising:
Resuming competition for the data transmission
Resuming contention for the data transmission based on the size of the contention window for the increased target network. Synchronizing at least one neighboring network and a target network in communication based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme;
Based on the number of the at least one neighboring network, allocating a reduction period of a backoff count for the at least one neighboring network and the target network, a slot index for the target network, and a size of a contention window Making;
Setting a value selected based on the size of the contention window as a back-off counter value for the target network;
Decrementing a value of a backoff counter for the target network based on a state of a channel; And
Based on whether the value of the backoff counter matches a first value and whether the value of the slot index for the target network matches the time slot for the at least one neighboring network and the target network. Transmitting Data for Neighbor Networks
Method for preventing a collision between networks communicating based on the CSMA / CA scheme comprising. The method of claim 7, wherein
The synchronizing step
Synchronize a time period between the at least one neighboring network and the target network by a first time period based on the number of the at least one neighboring network,
A method for preventing collisions between networks communicating based on a CSMA / CA scheme that synchronizes a time period within the target network by a second time period distinct from the first time period. The method of claim 7, wherein
Allocating a slot index for the target network
Between networks communicating based on the CSMA / CA scheme of allocating a slot index for the target network using a system parameter including at least one of a beacon shifting sequence index and a network ID. How to avoid the crash. The method of claim 7, wherein
Decreasing the value of the backoff counter for the target network
And reducing a value of a backoff counter for the target network based on whether the state of the channel is idle. The method of claim 7, wherein
Resuming contention for the data transmission based on whether a response to the data transmission has been received.
How to prevent the collision between the networks communicating based on the CSMA / CA method further comprising. 12. The method of claim 11,
Determining whether the size of the contention window for the target network is smaller than the size of the maximum contention window for the at least one neighboring network and the target network; And
Increasing the contention window size for the target network based on the determination result;
Further comprising:
Resuming competition for the data transmission
Resuming contention for the data transmission based on the size of the contention window for the increased target network. 13. A computer-readable recording medium on which a program for performing the method of any one of claims 1 to 12 is recorded. A synchronization unit for synchronizing at least one neighboring node and a target node to communicate with each other based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme;
A reduction period of a backoff counter for the at least one neighbor node and the target node, a slot index for the target node, and a content window based on the number of the at least one neighbor node; An allocating unit for allocating a size of the;
A setting unit configured to set a value selected based on the contention window size as a back-off counter value for the target node;
A reduction unit for decreasing a value of a backoff counter for the target node based on a state of a channel and a value of the assigned slot index; And
Transmitter for transmitting data for the at least one neighbor node according to the value of the back off counter
Target node for preventing collisions between networks communicating based on the CSMA / CA scheme comprising a. 15. The method of claim 14,
The synchronization unit
Synchronize a time period between the at least one neighboring node and the target node by a first time period based on the number of the at least one neighboring node,
A target node for preventing collisions between networks communicating based on a CSMA / CA scheme that synchronizes a time period within the target node by a second time period distinct from the first time period. 15. The method of claim 14,
The assigning unit
Between networks communicating based on the CSMA / CA scheme of allocating a slot index for the target node using a system parameter including at least one of a beacon shifting sequence index and a network ID. Target node to prevent collisions. 15. The method of claim 14,
The reduction portion
Decrease a value of a backoff counter for the target node based on whether the channel state is idle and the assigned slot index matches the index of the time slots for the at least one neighbor node and the target node. A target node for preventing collision between networks communicating based on the CSMA / CA scheme. A synchronization unit for synchronizing at least one neighboring node and a target node to communicate with each other based on a carrier sense multiple access / collision avoidance (CSMA / CA) scheme;
Based on the number of the at least one neighbor node, allocating a reduction period of a backoff count for the at least one neighbor node and the target node, a slot index for the target node, and a size of a content window. Allocating unit;
A setting unit configured to set a value selected based on the contention window size as a back-off counter value for the target node;
A reduction unit for reducing a value of a backoff counter for the target node based on a state of a channel; And
The at least one based on whether the value of the backoff counter matches a first value and whether a value of a slot index for the target node matches a time slot for the at least one neighbor node and a target node. Transmitter transmitting data for neighboring node
Target node for preventing collisions between networks communicating based on the CSMA / CA scheme comprising a. 19. The method of claim 18,
The synchronization unit
Synchronize a time period between the at least one neighboring node and the target node by a first time period based on the number of the at least one neighboring node,
A target node for preventing collisions between networks communicating based on a CSMA / CA scheme that synchronizes a time period within the target node by a second time period distinct from the first time period. 19. The method of claim 18,
The reduction portion
Target node preventing collisions between networks communicating based on a CSMA / CA scheme that reduces a value of a backoff counter for the target node based on whether the state of the channel is idle.

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